Natural Selection and Social Theory: Selected Papers of Robert L. Trivers

By Robert Trivers | Go to book overview

The 2nd: 4th Digit Ratio and Asymmetry of
Hand Performance in Jamaican Children
J. T. MANNING, R. L. TRIVERS, R. THORNHILL, AND D. SINGH

Abstract. Testosterone, particularly prenatal testosterone, has been implicated in the aetiology of many extragenital sexually dimorphic traits. It is difficult to test directly for the effect of prenatal testosterone in humans. However, Manning, Scutt, Wilson, and Lewis-Jones (1998b) have recently shown that the ratio of the length of the 2nd and 4th digits (2D: 4D) in right hands negatively predicts testosterone levels in men. As digit ratios are fixed in utero it may be that the 2D: 4D ratio is associated with many prenatally determined sexually dimorphic traits. We tested this for one case by examining the relationship between lateralised hand performance (LHP), as measured by an Annett peg board, and 2D: 4D ratio in rural Jamaican children. 2D: 4D ratio was measured from photocopies and X rays of hands. A low 2D: 4D ratio in the right hand of boys and girls (photocopies) and the right hand of boys only (X rays) was associated with a reduction in rightward performanceasymmetry. In both samples the difference in 2D: 4D ratio between the hands (2D: 4D left hand–2D: 4D right hand) showed the strongest relationship with LHP, i.e., high ratio in the left and low in the right correlated with a tendency towards a fast performance with the left hand. It is suggested that the 2D: 4D ratio may be associated with the expression of other sexually dimorphic behavioural traits.

Prenatal testosterone has been implicated as an important factor in the development of extragenital sexual dimorphism including the differentiation of the nervous system (Bardin & Caterall, 1981; McEwen, 1981; MacLusky & Naftolin, 1981). One such dimorphism may be seen in the expression of hand preferences (Geschwind & Behan, 1982; Geschwind & Galaburda, 1985; Hassler & Gupta, 1993). Geschwind and Galaburda (1985) have hypothesised that testosterone may slow growth within some areas of the left hemisphere and promote growth of certain areas in the right hemisphere. Such a process may mean that high levels of testosterone in utero would be associated with left-handedness and this left-preference could be seen in higher frequencies in males.

The Geschwind and Galaburda model is controversial. The model predicts association between left-handedness and lateralised hand performance and such things as auto-immune disorders, autism, and dyslexia. Not all of

-316-

Notes for this page

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Default project is now your active project.
Project items

Items saved from this book

This book has been saved
Highlights (0)
Some of your highlights are legacy items.

Highlights saved before July 30, 2012 will not be displayed on their respective source pages.

You can easily re-create the highlights by opening the book page or article, selecting the text, and clicking “Highlight.”

Citations (0)
Some of your citations are legacy items.

Any citation created before July 30, 2012 will labeled as a “Cited page.” New citations will be saved as cited passages, pages or articles.

We also added the ability to view new citations from your projects or the book or article where you created them.

Notes (0)
Bookmarks (0)

You have no saved items from this book

Project items include:
  • Saved book/article
  • Highlights
  • Quotes/citations
  • Notes
  • Bookmarks
Notes
Cite this page

Cited page

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited page

Bookmark this page
Natural Selection and Social Theory: Selected Papers of Robert L. Trivers
Table of contents

Table of contents

  • Title Page *
  • Preface vii
  • Contents *
  • Natural Selection and Social Theory *
  • 1 - Reciprocal Altruism 3
  • The Evolution of Reciprocal Altruism *
  • List of Literature *
  • Postscript *
  • 2 - Parental Investment and Reproductive Success 56
  • Parental Investment and Sexual Selection 65
  • Notes *
  • References 104
  • Postscript *
  • 3 - The Trivers-Willard Effect 111
  • Natural Selection of Parental Ability to Vary the Sex Ratio of Offspring 115
  • References and Notes *
  • Postscript *
  • 4 - Parent–offspring Conflict 123
  • Parent–offspring Conflict *
  • Notes *
  • References *
  • Postscript *
  • 5 - Haplodiploidy and the Social Insects 154
  • Haplodiploidy and the Evolution of the Social Insects - The Unusual Traits of the Social Insects Are Uniquely Explained by Hamilton's Kinship Theory *
  • References and Notes *
  • Postscript 206
  • 6 - Size and Reproductive Success in a Lizard 207
  • Sexual Selection and Resource-Accruing Abilities in Anolis Garmani *
  • Literature Cited *
  • Postscript *
  • 7 - Selecting Good Genes for Daughters 241
  • Asymmetry in the Evolution of Female Mating Preferences *
  • References *
  • Postscript *
  • 8 - Self-Deception in Service of Deceit 255
  • The Crash of Flight 90 - Doomed by Self-Deception? *
  • Postscript *
  • The Elements of a Scientific Theory of Self-Deception *
  • References *
  • Postscript 293
  • 9 - Genomic Imprinting 294
  • Genetic Conflicts in Genomic Imprinting *
  • Note 306
  • References *
  • Postscript 308
  • 10 - Fluctuating Asymmetry and the 2nd: 4th Digit Ratio in Children 309
  • The 2nd: 4th Digit Ratio and Asymmetry of Hand Performance in Jamaican Children 316
  • Notes *
  • References *
  • Postscript 328
  • References 329
  • Index 335
Settings

Settings

Typeface
Text size Smaller Larger Reset View mode
Search within

Search within this book

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

Full screen
/ 345

matching results for page

Cited passage

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited passage

Thanks for trying Questia!

Please continue trying out our research tools, but please note, full functionality is available only to our active members.

Your work will be lost once you leave this Web page.

For full access in an ad-free environment, sign up now for a FREE, 1-day trial.

Already a member? Log in now.